Many types of ligand-receptor assays have been used to detect the presence of various substances in body fluids, such as urine, saliva, or blood. Some commercially available assays are designed to make a quantitative determination, but in many circumstances all that is required is a qualitative positive/negative indication. Examples of such qualitative assays include blood typing, pregnancy testing, and many types of urinalysis.
U.S. Pat. No. 6,485,982, which is incorporated herein by reference in its entirety, describes a diagnostic test cell or device formed of an elongate outer casing which houses an interior permeable material (such as glass fiber) capable of transporting an aqueous solution by capillary action, wicking, or simple wetting. The casing defines a sample inlet, and interior regions, which are designated as a test volume and a reservoir volume. The reservoir volume is disposed in a section of the test cell spaced apart from the inlet and is filled with sorbent material. The reservoir acts to receive a fluid sample transported along a flow path defined by the permeable material and extending from the inlet and through the test volume. In the test volume is a test site comprising a first protein having a binding site specific to a first epitope of the ligand immobilized in fluid communication with the flow path (e.g., bound to the permeable material or to latex particles entrapped in or bonded to the permeable material). A window, such as a hole or transparent section of the casing, permits observations of the test site through the casing wall. The method of use of the test cell requires the use of a conjugate comprising a second protein bound to colored particles, such as a metal sol or colloid, preferably gold. The conjugate can take two distinct forms, depending on whether the assay is designed to exploit the “sandwich” or “competitive” technique.
U.S. Pat. No. 7,045,342, which is incorporated herein by reference in its entirety, describes a diagnostic test device including a biphasic chromatographic medium. The biphasic substrate is formed of a release medium joined to a capture medium located downstream of the release medium. The release and capture media preferably comprise two different materials, or phases, having different specific characteristics. The two phases are joined together to form a single fluid path such that a solvent front can travel unimpeded from the proximal (upstream) end of the release medium to the distal (downstream) end of the capture medium.
For tests such as those described above, visually observable indicia can be preferred. Such indicia typically have included the presence of agglutination or a color change at a defined site on the assay. More recent efforts have included providing electronic (i.e., digital) signals as the observable indicia. Nevertheless, user interface with diagnostic test devices remain limited. For example, user interface disconnect can lead to user anxiety, such as in relation to uncertainty over the elapsed time between starting a test and obtaining the test result. In typical pregnancy test devices, for example, the elapsed time is typically less than five minutes. During this time, there also can be anxiety over whether the test is indeed progressing normally. For example, although some test devices include a liquid crystal display (LCD) digital readout that can display a static or blinking clock as indicia of a progressing test, such interface can be sufficiently limited so as to not meet user expectations and overcome anxiety. Another user interface disconnect can relate to user uncertainty over whether a sufficient volume of fluid sample (e.g., urine) has been applied in order for the test to progress normally and provide a valid test result. Because of these and other reasons, it would be beneficial to provide a personal use test device with improved communication between the test device and the user.